If you place a strong acid in water it will likely ionize. If you put the same acid in oil it will not. Why the difference?

Answer

An acid that breaks down completely and gives off many ions, or protons, is considered to be a strong acid. ex H₂SO₄

If you place strong acid into water it dissociate acid into H⁺ ions

Water is polar solvent (H⁺ and OH⁻), which has partial positive charge on one side and partial negative charge on the other side.

Strong acids readily dissociate in polar solvents to give H + ions.

Where as Oil is a non polar solvent it has same charge all over so no dissociation of strong acid will take place.